The fuel system in your vehicle is under intense pressure. If you were to change the fuel filter in your Ford without relieving the fuel system pressure, you would risk a severe injury. There are two methods of depressurising a Ford fuel line. The first is primarily used on Ford trucks and the second is primarily used on Ford cars.
Open your hood and loosen the nut from your negative battery cable. Once the nut is off, lift the cable from the terminal. The negative battery cable must be disconnected when using the pressure valve method. Unscrew the gas cap when you are finished.
Locate the cap on the fuel supply manifold. Slip the cap off and connect the pressure gauge to the pressure relief valve.
Use the valve to drain the fuel into a sealable container, such as a plastic jug or a drain pan.
Wait for the excess fuel to drain and then press the pressure relief button. Unhook the pressure gauge from the fuel supply manifold and replace the cap.
Repressurize the fuel system after you finish replacing the fuel filter. Reconnect the negative battery cable and gas cap. Turn your ignition on for a few seconds, and then turn it off. Repeat this a few times to repressurize the fuel system.
Remove the fuel pump relay. For most vehicles, the relay is in the engine bay fuse box. If you have difficulty locating it, consult your owner's manual fuse diagram.
Unscrew the gas cap and keep the fuel access door open.
Crank the engine for about five seconds. If it starts, let it idle until it sputters and shuts off. To relieve fuel system pressure, you'll have to burn the excess fuel in the fuel lines.
Disconnect your negative battery cable before you begin replacing your fuel filter.
Reconnect the negative battery cable, gas cap and fuel pump relay when you are finished replacing the fuel filter. Turn the ignition on for a few seconds, and then turn it off. Repeat this for a few cycles to rebuild your fuel system pressure.
The pressure relief valve method must be performed on most Ford trucks and SUVs. Most Ford car fuel lines can be depressurised using the relay method. Check your owner's manual to be sure.
Use caution when working around a vehicle's fuel system. Don't smoke or perform the procedure near flames. Always wear gloves and goggles when you are replacing a fuel filter.